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Showing papers in "Cosmic Research in 2013"


Journal ArticleDOI
TL;DR: In this article, the design of the plasma spectrometer BMSW (Fast Monitor of the Solar Wind, possessing high temporal resolution) is described, as well as its characteristics and modes of operation.
Abstract: Design of the plasma spectrometer BMSW (Fast Monitor of the Solar Wind, possessing high temporal resolution) is described in the paper, as well as its characteristics and modes of operation. Some examples of measurements of various properties of the solar wind, made with this instrument installed onboard the high-apogee satellite Spektr-R, are presented.

49 citations


Journal ArticleDOI
TL;DR: In this paper, the first results of all-sky polarization measurements of the twilight background started in central Russia in the very beginning of summer 2011 and were described in detail in detail.
Abstract: The paper describes the first results of all-sky polarization measurements of the twilight background started in central Russia in the very beginning of summer 2011. Time-frequency data of the sky intensity and polarization over a wide range of sky point zenith distances are used to separate single and multiple scattering and construct the altitude dependence of the scattering coefficient and polarization in the mesosphere (altitudes from 60 to 90 km) at different angles. The undisturbed structure of the mesosphere without noticeable aerosol stratification on observation days makes it possible to estimate the temperature of the atmosphere at these altitudes.

23 citations


Journal ArticleDOI
TL;DR: The main phase of magnetic storms is approximated by a linear dependence on the main parameters of the solar wind: integral electric field sumEy, dynamic pressure Pd, and fluctuation level sB in IMF.
Abstract: Results of modeling the time behavior of the Dst index at the main phase of 93 geomagnetic storms (-250 < Dst ≤ -50 nT) caused by different types of solar wind (SW) streams: magnetic clouds (MC, 10 storms), corotating interaction regions (CIR, 31 storms), the compression region before interplanetary coronal ejec� tions (Sheath before ICME, 21 storms), and "pistons" (Ejecta, 31 storms) are presented. The "Catalog of LargeScale Solar Wind Phenomena during 1976-2000" (ftp://ftp.iki.rssi.ru/pub/omni/) created on the basis of the OMNI database was the initial data for the analysis. The main phase of magnetic storms is approx� imated by a linear dependence on the main parameters of the solar wind: integral electric field sumEy, dynamic pressure Pd, and fluctuation level sB in IMF. For all types of SW, the main phase of magnetic storms is better modeled by individual values of the approximation coefficients: the correlation coefficient is high and the standard deviation between the modeled and measured values of Dst is low. The accuracy of the model in question is higher for storms from MC and is lower by a factor of ~2 for the storms from other types of SW. The version of the model with the approximation coefficients averaged over SW type describes worse varia� tions of the measured D st index: the correlation coefficient is the lowest for the storms caused by MC and the highest for the Sheathand CIRinduced storms. The mo del accuracy is the highest for the storms caused by Ejecta and, for the storms caused by Sheath, is a factor of ~1.42 lower. Addition of corrections for the prehis� tory of the development of the beginning of the main phase of the magnetic storm improves modeling param� eters for all types of interplanetary sources of storms: the correlation coefficient varies within the range from r = 0.81 for the storms caused by Ejecta to r = 0.85 for the storms caused by Sheath. The highest accuracy is for the storms caused by MC. It is, by a factor of ~1.5, lower for the Sheathinduced storms.

17 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the basic problems arising in the solution of problems of the optimum control of spacecraft trajectory motion (including the Lyapunov instability of solutions of conjugate equations) using the principle of the maximum.
Abstract: The present paper1 analyzes the basic problems arising in the solution of problems of the optimum control of spacecraft (SC) trajectory motion (including the Lyapunov instability of solutions of conjugate equations) using the principle of the maximum. The use of quaternion models of astrodynamics is shown to allow: (1) the elimination of singular points in the differential phase and conjugate equations and in their partial analytical solutions; (2) construction of the first integrals of the new quaternion; (3) a considerable decrease of the dimensions of systems of differential equations of boundary value optimization problems with their simultaneous simplification by using the new quaternion variables related with quaternion constants of motion by rotation transformations; (4) construction of general solutions of differential equations for phase and conjugate variables on the sections of SC passive motion in the simplest and most convenient form, which is important for the solution of optimum pulse SC transfers; (5) the extension of the possibilities of the analytical investigation of differential equations of boundary value problems with the purpose of identifying the basic laws of optimum control and motion of SC; (6) improvement of the computational stability of the solution of boundary value problems; (7) a decrease in the required volume of computation.

17 citations


Journal ArticleDOI
TL;DR: In this paper, an active magnetic control synthesis for attitude guidance of a microsatellite is considered, where the only information required is the data from the sun sensor, and the applicability of a control to achieve solar panels sun-pointing is studied.
Abstract: An active magnetic control synthesis for attitude guidance of “Chibis-M” microsatellite is considered. The only information required is the data from the sun sensor. Applicability of a control to achieve solar panels sun-pointing is studied. Equations of motions are analytically solved using averaging technique. The behavior of a system with respect to initial conditions and orbit parameters is studied.

17 citations


Journal ArticleDOI
TL;DR: The laws of distribution of the space angle of attack for a light descent capsule on the atmosphere's conventional boundary and on the segment of motion in dense layers of the atmosphere until the moment of reaching the maximum velocity head were analyzed in this paper.
Abstract: The laws of distribution of the space angle of attack are analyzed for a light descent capsule on the atmosphere’s conventional boundary and on the segment of motion in dense layers of the atmosphere until the moment of reaching the maximum velocity head. It is assumed that upon detachment from a base spacecraft the angular velocity components of the descent capsule represent independent random quantities distributed according to the normal law. The shape of the descent capsule is close to a body of revolution whose instantaneous aerodynamic characteristic has a sufficiently simple form (one stable and one unstable positions of static equilibrium). It is demonstrated that there is a possibility to approximate the distribution densities by well-known laws and by approximate functions constructed on the basis of simplified models. Evolution of the distribution laws at increasing mass-inertia asymmetry of the descent capsule is studied.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the attitude dynamics of a fast rotating triaxial satellite under gravity-gradient is revisited, and two canonical transformations reduce the perturbed problem to its secular terms.
Abstract: The attitude dynamics of a fast rotating triaxial satellite under gravity-gradient is revisited. The essentially unique reduction of the Euler-Poinsot Hamiltonian, which can be performed in different sets of variables, provides a suitable set of canonical variables that expedites the perturbation approach. Two canonical transformations reduce the perturbed problem to its secular terms. The secular Hamiltonian and the transformation equations of the averaging are computed in closed form of the triaxiality coefficient, thus being valid for any triaxial body. The solution depends on Jacobi elliptic functions and integrals, and applies to non-resonant rotations under the assumption that the rotation rate is much higher than the orbital or precessional motion.

14 citations


Journal ArticleDOI
TL;DR: The tasks of the Plasma-F experiment onboard the Spectr-R satellite, as well as its structure and parameters, are described in this paper, where the authors also present a detailed description of the structure of the satellite.
Abstract: The tasks of the Plasma-F experiment onboard the Spectr-R satellite, as well as its structure and parameters, are described in the paper.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the ionospheric response to solar flares for the case of the beginning of solar activity growth, when the background ionization of the ionosphere is still low enough.
Abstract: The ionospheric response to solar flares is analyzed for the case of the beginning of solar activity growth, when the background ionization of the ionosphere is still low enough. It is shown that the algorithms and methods of averaging variations and derivative of the total electron content (TEC) over the entire sunlit ionosphere almost always make it possible to identify the ionospheric response even to close in time weak solar flares of the C class. It is found that the response to a solar flare rather intense in the X-ray range can have almost no manifestations, which is caused by the fact that the flare does not reveal itself in the ultraviolet part of the spectrum. A map of the TEC derivative over the Japan territory with an average resolution of ∼18 km is drawn for the M6.4 flare (February 7, 2010). Before the flare maximum, the TEC derivatives are synchronously increasing over the entire Japan, while after the flare maximum the values of the TEC derivative vary not so synchronously, and local differences are seen.

12 citations


Journal ArticleDOI
TL;DR: Based on a new database on positions of the auroral oval boundaries including measurements made by the IMAGE satellite in 2000-2002 with correct determination of the glow boundaries, statistical estimations of the latitudinal position of the polar cap boundary (PCB) are obtained in this paper.
Abstract: Based on a new database on positions of the auroral oval boundaries including measurements made by the IMAGE satellite in 2000–2002 with correct determination of the glow boundaries, statistical estimations of the latitudinal position of the polar cap boundary (PCB) are obtained depending on the IMF B y and B z , and the PCB evolution during a magnetic storm is analyzed. At zero IMF in the noon (midnight) sector, PCB is located approximately at 80° (76°) CGMLat. The PCB displacement along the noon-midnight meridian is controlled by the IMF B z , and in the noon (midnight) sector it is equal to 0.45° (0.15°) CGMLat when B z changes by 1 nT. The PCB displacement along the dawn-dusk meridian depends on the IMF B y , and it equals 0.1° CGMLat when B y changes by 1 nT. Accordingly, the north polar cap as a whole is shifted to the dawn (dusk) side at B y > 0 (B y <0). After northward turn of the IMF during the storm’s recovery phase, the PCB on the dayside is shifted to the north practically without time delay. The night boundary requires 25 h or more in order to be shifted to the pole to a latitude corresponding to B z > 0.

11 citations


Journal ArticleDOI
TL;DR: In this article, the gamma-ray burst monitor in the gamma range (the BDRG instrument) and the wide-field optical cameras (the SHOK instrument) were used for detecting both the gamma ray burst prompt emission and its precursors.
Abstract: One of the goals of the Lomonosov satellite designed by scientists of Moscow State University is to study the prompt emission of cosmic gamma-ray bursts. This paper describes the gamma-ray burst monitor in the gamma-ray range (the BDRG instrument) and the wide-field optical cameras (the SHOK instrument) for detecting both the gamma-ray burst prompt emission and its precursors.

Journal ArticleDOI
TL;DR: In this paper, the authors considered the planar circular Hill's problem and its limiting integrable variant called the Henon problem, for which the original hill's problem is a singular perturbation.
Abstract: The planar circular Hill’s problem is considered, as well as its limiting integrable variant called the Henon problem, for which the original Hill’s problem is a singular perturbation. Among solutions to the Henon problem there are a countable number of generating solutions-arcs that are uniquely determined by the condition of successive passage through the origin of coordinates—singular point of equations of motion of the Hill’s problem. Using the generating solutions-arcs as “letters” of a certain “alphabet”, one can compose, according to some rules, the “words”: generating solutions of families of periodic orbits of the Hill’s problem. The sequence of letters in a word determines the order of orbit transfer from one invariant manifold to another, while the set of all properly specified words determine the system’s symbolic dynamics.

Journal ArticleDOI
TL;DR: In this article, the authors performed spectral processing of the data of experiments on radio sounding of coronal plasma by coherent S- and X-band signals from the spacecraft Ulysses, Mars Express, Rosetta, and Venus Express carried out from 1991 to 2009.
Abstract: We have performed spectral processing of the data of experiments on radio sounding of circumsolar plasma by coherent S- and X-band signals from the spacecraft Ulysses, Mars Express, Rosetta, and Venus Express carried out from 1991 to 2009. The experiments were realized in the mode of coherent response, when a signal stabilized by the hydrogen standard is transmitted from the ground station to a spacecraft, received by the onboard systems, and retransmitted to the Earth with conserved coherence. Thus, the signal sounding the coronal plasma passes twice through the medium: on the propagation path ground station — spacecraft and on the same path in the opposite direction. The spectra of frequency fluctuations in both the bands are obtained and, using them, the radial dependences of fluctuation intensities are found, which can be approximated by a power law. It is shown that the ratio of intensities of frequency fluctuations in the S- and X-bands is comparable with the theoretical value and characterizes the degree of correlation of irregularities of the electron density along the propagation path ground station — spacecraft and back. Analysis of the correlation of frequency fluctuations on the two paths allows one to get a lower estimate of the outer scale of the circumsolar plasma turbulence. For heliocentric distances R = 10 solar radii (R S ) the outer scale is larger than 0.25R S .

Journal ArticleDOI
TL;DR: In this paper, a study of the response of the thermosphere and ionosphere to sudden stratospheric warmings (SSWs) which occurred in 2008 and 2009 is presented.
Abstract: A study of the response of the thermosphere and ionosphere to sudden stratospheric warmings (SSWs) which occurred in January of 2008 and 2009 is presented. The Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP) developed in the West Department of IZMIRAN was a theoretical basis for this study. A comparison of the simulation results of the thermosphere-ionosphere response to SSW events with the observational data over Irkutsk and also with theoretical and experimental studies carried out during the recent years is performed. SSW events were modeled by setting disturbances in the neutral temperature and density at the lower boundary of the GSM TIP model (80 km above the Earth’s surface). It is shown that the disturbances related to SSW lead to substantial global effects in the thermosphere and ionosphere. The analysis of the experimental data showed that, in spite of very similar solar and geophysical conditions on the background of which two considered stratospheric warming events happened, the occurring disturbances in temperature at heights of the mesosphere and lower thermosphere differ substantially from each other, although some common regularities still take place especially at heights of the ionospheric F region.

Journal ArticleDOI
TL;DR: In this paper, the main characteristics of the scientific equipment aboard the Lomonosov satellite are considered, and the main goal of this mission is to study extreme astrophysical phenomena such as cosmic gamma-ray bursts and ultra-high-energy cosmic rays.
Abstract: At present, the Institute of Nuclear Physics of Moscow State University, in cooperation with other organizations, is preparing space experiments onboard the Lomonosov satellite. The main goal of this mission is to study extreme astrophysical phenomena such as cosmic gamma-ray bursts and ultra-high-energy cosmic rays. These phenomena are associated with the processes occurring in the early universe in very distant astrophysical objects, therefore, they can provide information on the first stages of the evolution of the universe. This paper considers the main characteristics of the scientific equipment aboard the Lomonosov satellite.

Journal ArticleDOI
TL;DR: In this article, the authors investigated periodic motions of the axis of symmetry of a model satellite of the Earth, which are similar to the motion of the longitudinal axes of the Mir orbital station in 1999 and the Foton-M3 satellite in 2007.
Abstract: We investigated periodic motions of the axis of symmetry of a model satellite of the Earth, which are similar to the motions of the longitudinal axes of the Mir orbital station in 1999–2001 and the Foton-M3 satellite in 2007. The motions of these spacecraft represented weakly disturbed regular Euler precession with the angular momentum vector of motion relative to the center of mass close to the orbital plane. The direction of this vector during the motion was not practically changed. The model satellite represents an axisymmetric gyrostat with gyrostatic moment directed along the axis of symmetry. The satellite moves in a circular orbit and undergoes the action of the gravitational torque. The motion of the axis of symmetry of this satellite relative to the absolute space is described by fourth-order differential equations with periodic coefficients. The periodic solutions to this system with special symmetry properties are constructed using analytical and numerical methods.

Journal ArticleDOI
TL;DR: In this paper, the authors considered two versions of a law for controlling the characteristic angular momentum of a gyrosystem and provided a very low level of quasistatic microaccelerations on board the satellite.
Abstract: The mode of monoaxial solar orientation of a designed artificial Earth satellite (AES), intended for microgravitational investigations, is studied. In this mode the normal line to the plane of satellite’s solar batteries is permanently directed at the Sun, the absolute angular velocity of a satellite is virtually equal to zero. The mode is implemented by means of an electromechanical system of powered flywheels or gyrodynes. The calculation of the level of microaccelerations arising on board in such a mode, was carried out by mathematical modeling of satellite motion with respect to the center of masses under an effect of gravitational and restoring aerodynamic moments, as well as of the moment produced by the gyrosystem. Two versions of a law for controlling the characteristic angular momentum of a gyrosystem are considered. The first version provides only attenuation of satellite’s perturbed motion in the vicinity of the position of rest with the required velocity. The second version restricts, in addition, the increase in the accumulated angular momentum of a gyrosystem by controlling the angle of rotation of the satellite around the normal to the light-sensitive side of the solar batteries. Both control law versions are shown to maintain the monoaxial orientation mode to a required accuracy and provide a very low level of quasistatic microaccelerations on board the satellite.

Journal ArticleDOI
TL;DR: In this article, the influence of SW parameters, interplanetary magnetic field (IMF), and geomagnetic activity on the propagation direction, polarization, and amplitude of pulsations is discussed.
Abstract: On the basis of data of two networks of Canadian stations and also of extraand intramagneto� spheric satellites, daytime longperiod geomagnetic p ulsations related to sudden impulses of the dynamic pressure of the solar wind (SW) are studied. The influence of SW parameters, interplanetary magnetic field (IMF), and geomagnetic activity on the propagation direction, polarization, and amplitude of pulsations is discussed. It is shown that at arrival front of the solar wind inhomogeneity at the place of its tangency, surface oscillations within the range of Pc5 geomagnetic pulsations are excited on the magnetopause, and they run away from the tangency point to the nighttime side with increasing amplitude and opposite polarization. The pulsation properties and the position of the runningawa y point are explained by the mechanism of their exci� tation on the magnetopause by the inclined front of the inhomogeneity and also by the Kelvin-Helmholtz instability. Increases in SW density observed ahead of the shock front were able to cause pulsation excitation onsets prior to the sudden storms commencement (SSC) front arrival. The observed increase in geomagnetic activity after SSC could change the direction of pulsation propagation from antisunward to sunward. The analysis of oscillation spectra made it possible to assume that pulsations with a frequency of the order of 2.5 mHz are of a global character, they are not related to oscillations in SW and are excited by sharp SSC

Journal ArticleDOI
TL;DR: The results of observations of interplanetary scintillations of a statistical ensemble of radio sources in the period of 2007-2011 are presented in this paper, where the authors show that the radial dependence of a mean scintillation index during a deep solar activity minimum of 2008-2009 occurs to be weaker than one could expect in the case of spherically symmetric geometry of the solar wind.
Abstract: The results of observations of interplanetary scintillations of a statistical ensemble of radio sources in the period of 2007–2011 are presented Observation were carried out in the monitoring regime with the BSA LPI radio telescope at the frequency 111 MHz Fluctuations of radio emission flux of all sources (a few hundred in total) were recorded 24 hours a day Those sources were investigated, which had a scintillating flux greater than 02 Jy and fell within the sky band of 8° width in declination, corresponding to radio telescope’s 16-beam system The statistical ensemble of radio sources is characterized by the mean variance of a scintillating radiation flux, which is proportional to the squared scintillation index It follows from the obtained data that the radial dependence of a mean scintillation index during a deep solar activity minimum of 2008–2009 occurs to be weaker than one could expect in the case of spherically symmetric geometry of the solar wind Suppression of a radial dependence of the mean scintillation index is explained by the effect of the heliospheric current sheet, which reveals itself in a high density of solar wind’s turbulent plasma in the helioequator plane It is shown that the level of scintillations, averaged over monthly series of observations, was changing synchronously with the solar activity level

Journal ArticleDOI
TL;DR: In this article, a new modification of the strict method of the synthesis of nonlinear discrete-continuous stabilization systems with uncertainties is described, which is based on the minimization of the guaranteed accuracy estimate calculated using vector Lyapunov functions.
Abstract: The paper presents the second part of the results of search studies for the development of a combined system of high-precision stabilization of the optical telescope for the designed Spectr-UF international observatory [1]. A new modification of the strict method of the synthesis of nonlinear discrete-continuous stabilization systems with uncertainties is described, which is based on the minimization of the guaranteed accuracy estimate calculated using vector Lyapunov functions. Using this method, the synthesis of the feedback parameters in the mode of precise inertial stabilization of the optical telescope axis is performed taking the design nonrigidity, quantization of signals over time and level, and errors of orientation meters, as well as the errors and limitation of control moments of executive engine-flywheels into account. The results of numerical experiments that demonstrate the quality of the synthesized system are presented.

Journal ArticleDOI
TL;DR: In this paper, a comparative analysis of the dynamics of SCR fluxes with energies of 1-100 MeV in the interplanetary environment according to the data of ACE and Wind spacecraft and within the Earth's magnetosphere according to data of the GOES-15 and Electro-L satellites, and POES-19 and Meteor-M1 in the region of polar caps during two increases in SCR of January 19-31, 2012, is presented.
Abstract: Results of the comparative analysis of the dynamics of SCR fluxes with energies of 1–100 MeV in the interplanetary environment according to the data of the ACE and Wind spacecraft and within the Earth’s magnetosphere according to the data of the GOES-15 and Electro-L satellites in the region of geostationary orbits, and POES-19 and Meteor-M1 in the region of polar caps during two increases in SCR of January 19–31, 2012, are presented. It is shown that the decrease in the efficiency of SCR penetration into the Earth’s magnetosphere in the region of the orbits under study on January 28, 2012, is related to the passage of the Earth’s magnetosphere through the interplanetary environment structure with a quasi-radial interplanetary magnetic field and a small pressure of the solar wind.

Journal ArticleDOI
TL;DR: In this article, the authors compare the behavior of pressure along the Sun-Earth line for the northward and radial interplanetary field, using the results of numerical MHD simulation and observational data from THEMIS.
Abstract: Based on analysis of MHD equations and the results of numerical simulation in the magneto-sheath it is demonstrated that the total pressure on the magnetopause differs from the solar wind dynamic pressure in the majority of cases. From the equation of motion it follows that the total pressure is reduced due to deflection from the Sun-Earth line. At the same time, it increases because of formation of a magnetic barrier. This result is consistent with experimentally observed expansion of the magnetosphere for the radial direction of the interplanetary magnetic field, when no magnetic barrier is formed. In this paper we compare the behavior of pressure along the Sun-Earth line for the northward and radial interplanetary field, using the results of numerical MHD simulation and observational data from THEMIS. In the isotropic MHD approximation, the difference between the total pressure on the subsolar magnetopause at northern and radial IMFs does not exceed 10–12 percent. However, in the anisotropic approximation this difference increases up to 15–20 percent. The results of anisotropic modeling well agree with observed averaged profiles of pressure components in the subsolar magnetosheath.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the excesses in the sum of fluxes in cosmic rays in the energy range (10-1000) GeV and in the flux ratio e¯¯¯¯ +/(e PsyNet + + + e¯¯¯¯ −) in the range > 10 GeV, observed both in recent and old experiments, can be explained by an accelerator of charged particles operating on the heliosphere periphery, in the region beyond the termination shock of the solar wind.
Abstract: It is shown that the excesses in the sum of fluxes (e + + e −) in cosmic rays in the energy range (10–1000) GeV and in the flux ratio e +/(e + + e −) in the range > 10 GeV, observed both in recent and old experiments, can be explained by an accelerator of charged particles operating on the heliosphere periphery, in the region beyond the termination shock of the solar wind (∼100 AU). Variations in the value and position of peculiarities in the spectra (e + + e −), as well as increasing ratio of fluxes e +/(e + + e −), can be associated with variations of solar activity (and, as a consequence, of acceleration regimes) on different phases of the 11-years solar cycle. The results of numerical simulation of capture and acceleration of charged particles by packets of plasma waves in the heliospheric magnetic field are presented.

Journal ArticleDOI
TL;DR: An integrated conceptual basis is used to develop multistep terminal algorithms for guidance for the three segments of the descent of a landing module designed for the Moon landing.
Abstract: The paper deals with a choice of the rational trajectory of motion of a landing module designed for the Moon landing, from the moment of its de-orbiting from the near-lunar orbit up to landing. An integrated conceptual basis is used to develop multistep terminal algorithms for guidance for the three segments of the descent.

Journal ArticleDOI
TL;DR: In this paper, the nonlinear game problem of the three-axis reorientation of an asymmetric solid body with three flywheels (rotors) has been solved and acceptable levels of uncontrollable noise depending on given constraints of control moments have been estimated.
Abstract: The nonlinear game problem of the three-axis reorientation of an asymmetric solid body with three flywheels (rotors) has been solved. Acceptable levels of uncontrollable noise depending on given constraints of control moments have been estimated.

Journal ArticleDOI
TL;DR: The paper presents the results of measurements of dose rate and particle fluxes caused by various radiation field components on the ISS during the period from June 2007 till December 2009.
Abstract: For estimating radiation risk in space flights it is necessary to determine radiation dose obtained by critical organs of a human body. For this purpose the experiments with human body models are carried out onboard spacecraft. These models represent phantoms equipped with passive and active radiation detectors which measure dose distributions at places of location of critical organs. The dosimetric Liulin-5 telescope is manufactured with using three silicon detectors for studying radiation conditions in the spherical tissue-equivalent phantom on the Russian segment of the International space station (ISS). The purpose of the experiment with Liulin-5 instrument is to study dynamics of the dose rate and particle flux in the phantom, as well as variations of radiation conditions on the ISS over long time intervals depending on a phase of the solar activity cycle, orbital parameters, and presence of solar energetic particles. The Liulin-5 dosimeter measures simultaneously the dose rate and fluxes of charged particles at three depths in the radial channel of the phantom, as well as the linear energy transfer. The paper presents the results of measurements of dose rate and particle fluxes caused by various radiation field components on the ISS during the period from June 2007 till December 2009.

Journal ArticleDOI
TL;DR: In this paper, the time behavior of cosmic rays with relatively low (~1-6 GeV) and high (>10 GeV), together with characteristics influencing the modulation of the cosmic rays in the heliosphere are considered.
Abstract: The time behavior of intensity of cosmic rays with relatively low (~1–6 GeV) and high (>10 GeV) energies are considered together with characteristics influencing the modulation of cosmic rays in the heliosphere. The periods under study are close to solar activity minima in cycles 21/22, 22/23, and 23/24. Diffusion and convection in small-scale magnetic fields of the heliosphere are demonstrated to play some role only at sufficiently weak disturbances of the field (B/δB > 1.3). In this case, a negative correlation is observed between B/δB and a tilt of the surface of the heliospheric current sheet. The analysis of characteristics of the interplanetary medium in periods of solar activity minima shows that the energy anomaly of cosmic rays in the minimum of cycles 23/24 is caused by deficit of high energy particles rather than by an excess of particles of relatively small energies.

Journal ArticleDOI
TL;DR: In this paper, the accuracy of orbit determination calculated by observations of short arcs was analyzed and the condition that the arc length and/or the distribution of arc observations should provide a confident classification of the orbit of a small celestial body allowing one to distinguish a potentially hazardous body, also including a threat of collision.
Abstract: This paper analyzes the accuracy of orbit determination calculated by observations of short arcs. In this case, we imposed the condition that the arc length and/or the distribution of arc observations should provide a confident classification of the orbit of a small celestial body allowing one to distinguish a potentially hazardous body, also including a threat of collision.

Journal ArticleDOI
TL;DR: In this paper, the formation and motion of six limb CMEs detected in the period June 2010 to June 2011 were investigated using the high-resolution data of the PROBA2 and SDO spacecraft combined with the data of SOHO/LASCO coronagraphs.
Abstract: Formation and motion (at the initial stage) of six limb CMEs detected in the period June 2010 to June 2011 are investigated using the high-resolution data of the PROBA2 and SDO spacecraft combined with the data of SOHO/LASCO coronagraphs. It is demonstrated that several loop-like structures of enhanced brightness originate in the region of CME formation, and they move one after another with, as a rule, different velocities. These loop-like structures in the final analysis form the frontal structure of CME. Time dependences of the velocity and acceleration of the ejection’s front are obtained for all CMEs under consideration. A conclusion is drawn about possible existence of two classes of CMEs depending on their velocity time profiles. Ejections, whose velocity after reaching its maximum sharply drops by a value of more than 100 km/s and then goes over into a regime of slow change, belong to the first class. Another class of CMEs is formed by ejections whose velocity changes slowly immediately after reaching the maximum. It is demonstrated that the CME’s angular dimension increases at the initial stage of ejection motion up to a factor of 3 with a time scale of doubling the angular size value within the limits 3.5–11 min since the moment of the first measurement of this parameter of an ejection. For three CMEs it is shown that at the initial stage of their motion for a certain time interval they are stronger expanded than grow in the longitude direction.

Journal ArticleDOI
TL;DR: In this paper, a simple method of finding the transfer trajectory is suggested, based on linearization of motion near reference orbits, and the required accuracy of calculations is achieved by way of increasing the number of reference orbits.
Abstract: Low-thrust transfers between preset orbits are considered in the presence of perturbations of different origin. A simple method of finding the transfer trajectory is suggested, based on linearization of motion near reference orbits. The required accuracy of calculations is achieved by way of increasing the number of reference orbits. The method can also be used in the case of a large number of revolutions around the attracting center: no averaging of motion is required in this case. The suggested method is applicable as well, when the final orbit is specified partially and when there are constraints on the thrust direction. The optimal solution to the linearized problem is not optimal for the original problem; closeness of solutions to these two problems is estimated using a numerical example. Capabilities of the method are also illustrated by examples.